X bought goods worth Rs. 500. He gets a rebate of 8% on it. After getting the rebate, he pays sales tax @ 12.5%. What is the final amount that he has to pay?

1. A

   Rs. 520

2. B

   Rs. 517.5

3. C

   Rs. 512

4. D

   Rs. 515

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

• The initial price of the goods is Rs. 500.
• An 8% rebate is applied first, which reduces the price to Rs. 460 (500 - (0.08 × 500)).
• A 12.5% sales tax is then calculated on this new price of Rs. 460, which amounts to Rs. 57.5 (0.125 × 460).
• The final price is the sum of the rebated price and the sales tax: 460 + 57.5 = Rs. 517.5.

Why Other Options Were Wrong

• Option A: This result may arise from incorrect calculation, such as netting the percentages (12.5% - 8% = 4.5%) and applying it incorrectly. For instance, adding 4% of 500 (which is 20) to 500 gives 520. This is wrong because the tax is calculated on the discounted price, not the original price, and percentages cannot be simply added or subtracted this way.
• Option C: This value likely results from a calculation error, possibly by incorrectly rounding the sales tax amount. For example, if the tax (Rs. 57.5) was incorrectly calculated or rounded down to Rs. 52, the final amount would be 460 + 52 = Rs. 512.
• Option D: This is another plausible calculation error. If the sales tax amount (Rs. 57.5) was incorrectly rounded down to Rs. 55, the final amount would be 460 + 55 = Rs. 515.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of final price involving percentage-based rebate and sales tax as background academic context rather than a clinical decision trigger.
• This question tests basic arithmetic and percentage calculation skills, which are part of the general aptitude section of nursing entrance exams.
• While not a clinical skill, mathematical proficiency is essential for nurses for tasks like medication dosage calculation, interpreting lab results, and managing fluid balances.
• What if? If the sales tax was applied before the rebate, the final price would be different. Tax on Rs. 500 would be Rs. 62.5 (500 × 0.125). The price would be 500 + 62.5 = Rs. 562.5. Then, an 8% rebate on Rs. 500 (Rs. 40) would be subtracted, leading to a final price of 562.5 - 40 = Rs. 522.5. The order of operations is critical.

How to Approach the Question

• First, identify the initial value (Rs. 500), the rebate percentage (8%), and the sales tax percentage (12.5%).
• Understand the standard order of operations: discounts/rebates are applied to the original price first to get a new base price.
• Calculate the rebate amount by converting the percentage to a decimal (8% = 0.08) and multiplying by the original price.
• Subtract the rebate from the original price to find the discounted price.
• Next, calculate the sales tax amount by applying the tax percentage to the discounted price, not the original price.
• Finally, add the sales tax amount to the discounted price to determine the total final cost.

Concept Tested & Keywords

• Concept Tested: Calculation of final price involving percentage-based rebate and sales tax.
• Stem keywords: goods worth, Rs. 500, rebate, 8%, sales tax, 12.5%, final amount
• Lead-in keywords: What is the final amount

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